The present invention relates to a polarizing plate with an optical compensation film for use in a liquid crystal display (hereinafter, abbreviated as xe2x80x9cLCDxe2x80x9d) with improved display irregularities, and to a liquid crystal display.
Optical compensation films are used in super twisted nematic (STN) LCDs in order to perform black and white display or color display. Furthermore, optical compensation films with uniaxially or biaxially stretched polymer films, and optical compensation films with oriented liquid crystal polymers are used in thin film transistor (TFT) LCDs in order to achieve a broad viewing angle.
Polarizing plates used in display devices (particularly in LCDs) are fabricated, for example, by dyeing a polyvinyl alcohol film (hereinafter, abbreviated as xe2x80x9cPVA filmxe2x80x9d) with iodine, which is dichroic, or a dichroic dye in a dyeing step, crosslinking the film with boric acid or borax, for example, in a crosslinking step, and stretching the film uniaxially in a stretching step. The steps for dyeing, crosslinking, and stretching do not have to be performed separately and can be performed simultaneously. There is no particularly specific order to the steps. After these steps, the PVA film is dried and a protective layer such as a triacetyl cellulose film (hereinafter, abbreviated as xe2x80x9cTAC filmxe2x80x9d) is adhered on it.
When a LCD panel is lit, the heat generated from the backlight, for example, warms the polarizing plate and the optical compensation film to 40 to 60xc2x0 C., and the polarizing plate and the optical compensation film are expanded by linear expansion. The polarizing plate and the optical compensation film are laminated on one another via an adhesive agent, however, the polarizing plate has a larger dimensional change. For that reason, stress due to the difference in dimensional change between the polarizing plate and the optical compensation film is applied to the optical compensation film side, which results in the generation of display irregularities in the LCD panel.
The present invention provides a polarizing plate with an optical compensation film for use in a LCD, and a liquid crystal display, in which display irregularities have been improved.
In embodiments of the present invention, a polarizing plate with an optical compensation film includes a polarizing plate, an adhesive layer A, an optical compensation film, and an adhesive layer B adhered to one another, wherein the polarizing plate comprises a polyvinyl alcohol polarizing film containing a dichroic substance, and wherein the elastic modulus of the adhesive layer A is 0.06 MPa or less.
In some embodiment of the invention, a liquid crystal display is furnished at least on one side of the liquid crystal cell with a polarizing plate with an optical compensation film including a polarizing plate, an adhesive layer A, an optical compensation film, and an adhesive layer B adhered to one another, wherein the polarizing plate comprises a polyvinyl alcohol polarizing film containing a dichroic substance, and wherein the elastic modulus of the adhesive layer A is 0.06 MPa or less.